Question

I have been researching this for some time, so if I missed a topic somewhere please point me in the right direction and accept my apologies.

I am performing a LINQ query on an incoming DataTable and setting up new columns based on the filtering done. The information being passed in is a single row containing the columns: CompanyName, CustomerID, LastName, FirstName, ContactTitle.

My question is, am I over-filtering the information to the point where it will return nothing to the DGV, or have I done something else wrong?

What I am trying to do is query another table based on the information passed in from the DataTable. Here is my query:

            var query = (from id in IncomingOrderDetails.AsEnumerable()
                    from o in db.Orders
                    from c in db.Customers
                    from r in db.Regions
                    where (id.Field<int>("OrderID") == o.OrderID)
                    where (o.CustomerID == c.CustomerID)
                    where (c.Region == r.RegionDescription)
                    select new
                    {
                        CustomerID = c.CustomerID,
                        CompanyName = c.CompanyName,
                        ContactName = c.ContactName,
                        RegionDescription = r.RegionDescription,
                        Country = c.Country,
                        Phone = c.Phone
                    }).ToList();

        custInfoDGV.DataSource = query;

Answer 1

This line:

 where (c.Region == r.RegionDescription)

…looks dubious. If c.Region = r.RegionDescription, why do you need to bring in r at all? All you use it for is retrieving the RegionDescription.

I don’t know your tables, but joining two fields that don’t match would certainly produce 0 records returned. 🙂